/*
 * mailod: optimalization of the usage disk
 * Author: Jan Garaj	
 * source: http://b-con.us/code/sha256_c.php
 */
 
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "hash_function.h"
 
// DBL_INT_ADD treats two unsigned ints a and b as one 64-bit integer and adds c to it 
#define DBL_INT_ADD(a,b,c) if (a > 0xffffffff - (c)) ++b;a += c; 
#define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b)))) 
#define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b)))) 
#define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z))) 
#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z))) 
#define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22)) 
#define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25)) 
#define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3)) 
#define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10)) 

uint k[64] = {
	0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
	0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
	0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
	0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
	0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
	0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
	0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
	0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2 
};

void sha256_transform(SHA256_CTX *ctx, uchar data[]) { 
	uint a,b,c,d,e,f,g,h,i,j,t1,t2,m[64];
	for (i=0,j=0; i < 16; ++i, j += 4) 
	  m[i] = (data[j] << 24) | (data[j+1] << 16) | (data[j+2] << 8) | (data[j+3]); 
	for ( ; i < 64; ++i) 
	  m[i] = SIG1(m[i-2]) + m[i-7] + SIG0(m[i-15]) + m[i-16]; 

	a = ctx->state[0]; 
	b = ctx->state[1];
	c = ctx->state[2]; 
	d = ctx->state[3]; 
	e = ctx->state[4]; 
	f = ctx->state[5]; 
	g = ctx->state[6]; 
	h = ctx->state[7]; 

	for (i = 0; i < 64; ++i) {
		t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i]; 
		t2 = EP0(a) + MAJ(a,b,c); 
		h = g; 
		g = f; 
		f = e; 
		e = d + t1; 
		d = c; 
		c = b; 
		b = a; 
		a = t1 + t2;
	} 

	ctx->state[0] += a;
	ctx->state[1] += b; 
	ctx->state[2] += c; 
	ctx->state[3] += d; 
	ctx->state[4] += e; 
	ctx->state[5] += f; 
	ctx->state[6] += g; 
	ctx->state[7] += h; 
} 

void sha256_init(SHA256_CTX *ctx) {
	ctx->datalen = 0; 
	ctx->bitlen[0] = 0;
	ctx->bitlen[1] = 0; 
	ctx->state[0] = 0x6a09e667; 
	ctx->state[1] = 0xbb67ae85; 
	ctx->state[2] = 0x3c6ef372; 
	ctx->state[3] = 0xa54ff53a; 
	ctx->state[4] = 0x510e527f; 
	ctx->state[5] = 0x9b05688c;
	ctx->state[6] = 0x1f83d9ab;
	ctx->state[7] = 0x5be0cd19; 
}

void sha256_update(SHA256_CTX *ctx, uchar data[], uint len) {
	uint i;
	for (i=0; i < len; ++i) { 
		ctx->data[ctx->datalen] = data[i];
		ctx->datalen++; 
		if (ctx->datalen == 64) { 
			sha256_transform(ctx,ctx->data); 
			DBL_INT_ADD(ctx->bitlen[0],ctx->bitlen[1],512);
			ctx->datalen = 0; 
		} 
	} 
}

void sha256_final(SHA256_CTX *ctx, uchar hash[]) {
	uint i; i = ctx->datalen; 
	// Pad whatever data is left in the buffer. 
	if (ctx->datalen < 56) {
		ctx->data[i++] = 0x80;
		while (i < 56) 
		  ctx->data[i++] = 0x00;
	} else {
		ctx->data[i++] = 0x80;
		while (i < 64) 
		  ctx->data[i++] = 0x00; 
		sha256_transform(ctx,ctx->data); 
		memset(ctx->data,0,56); 
	} 

	// Append to the padding the total message's length in bits and transform. 
	DBL_INT_ADD(ctx->bitlen[0],ctx->bitlen[1],ctx->datalen * 8);
	ctx->data[63] = ctx->bitlen[0];
	ctx->data[62] = ctx->bitlen[0] >> 8;
	ctx->data[61] = ctx->bitlen[0] >> 16; 
	ctx->data[60] = ctx->bitlen[0] >> 24; 
	ctx->data[59] = ctx->bitlen[1];
	ctx->data[58] = ctx->bitlen[1] >> 8; 
	ctx->data[57] = ctx->bitlen[1] >> 16; 
	ctx->data[56] = ctx->bitlen[1] >> 24; 
	sha256_transform(ctx,ctx->data);
	 
	// Since this implementation uses little endian byte ordering and SHA uses big endian, 
	// reverse all the bytes when copying the final state to the output hash. 
	for (i=0; i < 4; ++i) {
		hash[i] = (ctx->state[0] >> (24-i*8)) & 0x000000ff; 
		hash[i+4] = (ctx->state[1] >> (24-i*8)) & 0x000000ff; 
		hash[i+8] = (ctx->state[2] >> (24-i*8)) & 0x000000ff; 
		hash[i+12] = (ctx->state[3] >> (24-i*8)) & 0x000000ff; 
		hash[i+16] = (ctx->state[4] >> (24-i*8)) & 0x000000ff; 
		hash[i+20] = (ctx->state[5] >> (24-i*8)) & 0x000000ff; 
		hash[i+24] = (ctx->state[6] >> (24-i*8)) & 0x000000ff; 
		hash[i+28] = (ctx->state[7] >> (24-i*8)) & 0x000000ff; 
	} 
}

char *hash_text(char *text) { 
	unsigned char hash[32];
	char *hash_out;
	SHA256_CTX ctx; 
	int idx; 
	
	if((hash_out=(char *) malloc(64*sizeof(char)))==NULL) {
		fprintf(stderr,"Error, mallock hash_out\n");
		return NULL;	
	}
	sha256_init(&ctx); 
	sha256_update(&ctx,(uchar *) text,strlen(text)); 
	sha256_final(&ctx,hash); 
	for (idx=0; idx < 32; idx++)
	  sprintf((hash_out+(2*idx)),"%02x",hash[idx]); 
	return hash_out;
}
